Eye Exam Essentials: Part 1

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Last year I wrote two articles discussing the pretest, which takes place with a technician prior to seeing your Optometrist. Pretest includes lensometry (glasses measurement), autorefraction (prescription starting point), intraocular pressure, visual field, retinal scans, and retinal photographs. Once the pretest is completed, you will be escorted to a sanitized exam room and seated in the exam chair. Your technician performs further cleaning of the equipment and prepares your scans on the computer for the doctor to view. 

Your Optometrist will introduce themselves and begin discussing the reason for your visit. If you are new, you will be asked the approximate date of your last eye exam. The main purpose of your visit is called the chief complaint. You may have no concerns and are just in for a routine exam or you may have several concerns with your eyes or vision. The more information you can provide to your Optometrist during this initial discussion, the better. Your Optometrist is trained to ask relevant probing questions such as frequency, onset, location, duration, associations, relief, and severity. An example for itchy eyes: Frequency (every day); Onset (two weeks ago); Location (both eyes); Duration (several hours per day); Associations (worse outdoors); Relief (cold compresses); Severity (bothersome but can still function). 

Details of your personal ocular and systemic health history, medications, allergies, and family history will be obtained. If you wear glasses, you will be asked how often you wear them, for what purpose, and how well they are working for you. If you wear contact lenses there will be additional history questions relating to your use of contacts. A careful and detailed case history can give us enough information to form a working diagnosis and helps us determine if additional tests, investigations, or solutions may be recommended during your visit. 

Visual acuity will be the first test performed by your Optometrist. This is measured at all eye exams including follow-up visits. Visual acuity involves reading letters (or pictures, numbers, or symbols) on the eye chart at both distance and near. It may be done without correction and/or with correction (glasses or contact lenses). One eye is covered at a time to give a reading of monocular acuity and then both together for binocular acuity. “Normal” visual acuity is recorded as 20/20, meaning that you can see clearly at 20 feet what would normally be seen at that distance. If you have 20/40 vision, this means that you must be as close as 20 feet to see something clearly that someone with “normal” vision can see from 40 feet away. If there is a reduction in visual acuity, your Optometrist may use something called a pinhole occluder. If the vision improves while looking through this tiny hole, we know optically that the vision should improve with new corrective lenses. If the pinhole does not improve vision, there may be an ocular health condition such as a cataract.

Another preliminary test is cover testing to investigate for any eye misalignment. You will be asked to look at targets in the distance and up close while your Optometrist moves an occluder from side to side. Extraocular motility testing is also done to see how your eyes move in all directions and to check how well your eyes converge towards your nose. A bright light will be shone in your eyes to check how your pupils react to light. In some cases, color vision, stereo acuity, and other tests will be done, depending on your age and symptoms. Visual acuity and these other preliminary tests take only minutes to complete but give your Optometrist valuable information. The results could even help us catch potentially serious ocular or general health conditions. In part 2 of this article, I will discuss refraction and ocular health testing. 

Written by Trevor Miranda

Dr. Miranda was raised in Simcoe, Ontario and graduated from the University of Waterloo with his Doctorate of Optometry in 1995. Following graduation, he moved to beautiful Vancouver Island, where he continues to serve the eye care needs of the Cowichan Valley. Trevor is also an active member of the Third World Eye Care Society and has participated with other professionals to improve the vision of the less fortunate. Dr. Miranda was named Optometrist of the Year by the British Columbia Association of Optometrists in March 2015. This prestigious honour recognized Dr. Miranda’s commitment to providing every patient with exceptional care while mentoring optometrists across Canada. Outside the office, you will find Trevor enjoying hockey, coaching soccer, involved with the South Cowichan Rotary Club, and spending time with his wife Cheryl and their three children. Trevor looks forward to continuing to care for the eyes of the Cowichan Valley and welcomes new patients without a referral. Dr. Miranda is available for appointments in our Duncan and Cobble Hill.
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